01Core principlesThe concepts and mechanisms needed to understand the subject.
IBD surgery risk is shaped by disease and treatment together. Active sepsis, obstruction, anaemia, weight loss, sarcopenia, smoking, corticosteroids, venous-thromboembolism risk and the planned anastomosis matter more than a single drug label. The preoperative visit should therefore translate each problem into an action, owner, target and review date. A low albumin can signal severe inflammation or protein loss as well as poor intake and cannot independently diagnose malnutrition.
Nutrition starts with a quantified assessment: current and usual weight, percentage weight loss and time course, BMI, recent intake, grip or muscle function where available, obstructive dietary limitation, haemoglobin and iron, B12, folate, vitamin D, renal and electrolyte status. If the gut works, oral diet and prescribed supplements or enteral feeding are preferred. The BSG guideline cites 7–10 days of support before major gastrointestinal surgery for mildly malnourished patients, with longer treatment for severe malnutrition when delay is safe. Emergency source control is never withheld to complete a feeding target.
Exclusive enteral nutrition may reduce inflammation and improve nutritional state in selected Crohn disease, especially undernourished stricturing or penetrating phenotypes, but BSG finds insufficient evidence for routine preoperative use. A dietitian must select formulation, route, energy and protein target and monitor tolerance. A patient with fixed high-grade obstruction may not safely tolerate full-volume enteral feeding, while someone with a drained abscess and functioning proximal gut may. Parenteral nutrition is a route decision for intestinal failure or failed enteral access, not a marker that care is more intensive.
Corticosteroids increase postoperative infective and healing risk and should be stopped before elective surgery if possible or reduced to the lowest clinically manageable dose. Abrupt cessation after sustained exposure risks adrenal insufficiency and disease relapse. BSG supplies maintenance equivalence—prednisolone 5 mg equals hydrocortisone 20 mg or methylprednisolone 4 mg—when oral treatment cannot be taken, but that conversion is not a complete adrenal stress plan. NICE NG243 and the ESE/Endocrine Society guidance require perioperative stress cover for current or recent users when glucocorticoid-induced adrenal insufficiency has not been excluded, with parenteral cover for major stress or general anaesthesia. The corrected Woodcock Table 2 provides the concrete major-surgery regimen for adults taking at least prednisolone 5 mg for four weeks or longer.
Biologic decisions are drug and context specific. BSG recommends that anti-TNF therapy can continue preoperatively in ulcerative colitis. Automatically withholding treatment can provoke disease deterioration, while active infection may require deferral and treatment. In Crohn disease and for vedolizumab, ustekinumab or small molecules, the team should use the current guideline, pharmacology, infection status, operation and need for disease control rather than a memorised universal washout. JAK inhibitors require particular attention to venous-thromboembolism risk and the limited perioperative evidence. Every decision needs a documented restart criterion after surgery.
Key points
- Screen every surgical IBD patient for recent weight loss, BMI, intake, muscle loss, anaemia and micronutrient deficiency; albumin also reflects inflammation and should not be used as a stand-alone nutrition score.
- Use oral food and supplements first when safe, then enteral tube feeding if intake remains inadequate; parenteral nutrition is reserved for a non-functioning or inaccessible gut or failure of enteral delivery.
- For mildly malnourished patients undergoing major gastrointestinal surgery, cited ESPEN practice supports 7–10 days of preoperative nutrition; severe malnutrition may justify longer delay when the disease is safe to defer.
- BSG says evidence is insufficient for routine preoperative exclusive enteral nutrition in every Crohn patient, but it can be considered in selected undernourished people with stricturing or penetrating disease.
- Before elective IBD surgery, stop corticosteroids if feasible or reduce them to the lowest dose that does not destabilise disease; recent dose and duration change infection, wound and adrenal planning.
- If oral prednisolone cannot be taken, calculate equivalent maintenance exposure separately: prednisolone 5 mg equals hydrocortisone 20 mg or methylprednisolone 4 mg. This arithmetic is not by itself the complete stress-cover prescription.
- Current or recent prednisolone at 5 mg/day or more for at least four weeks can suppress the HPA axis. For major surgery under anaesthesia without excluded adrenal insufficiency, the corrected Woodcock table uses hydrocortisone 100 mg IV at induction then 200 mg/24 hours while nil by mouth, followed by a defined enteral transition.
- BSG explicitly allows preoperative anti-TNF continuation for ulcerative colitis. For other biologics and small molecules, record drug, last dose, infection status and disease risk and agree the plan across IBD, surgical, anaesthetic and pharmacy teams.
- Peritonitis, uncontrolled sepsis, perforation or complete obstruction needs resuscitation and source control; optimisation proceeds in parallel and must not create a dangerous delay.
02Mechanisms and patternsImportant relationships and how to distinguish them.
Percentage loss over one to six months is more informative than today’s weight alone and should trigger dietitian review before an elective major operation.
Reduced muscle bulk, grip, mobility or radiological muscle area can identify physiological depletion in a patient whose BMI appears reassuring.
Postprandial pain, vomiting and a low-residue self-restricted diet may prevent safe oral targets and require imaging before enteral volume is increased.
Record preparation, current dose, highest recent dose, total duration and previous taper failure; “on steroids” is insufficient for conversion or risk planning.
Fever, abscess, draining sepsis, pneumonia or line infection changes both operative source control and whether a biologic dose is administered.
Active IBD, surgery, immobility, previous VTE, cancer, corticosteroids and JAK inhibitors can combine, requiring mechanical and pharmacological prophylaxis planning.
03Interpreting evidenceInformation, measurements and their limitations.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
Weight history, BMI and validated malnutrition screen - Why
- Quantify recent loss and identify who needs urgent dietetic assessment and preoperative support.
- Interpretation and limitations
- An apparently stable BMI does not exclude sarcopenia; percentage weight loss and reduced intake change urgency and route.
- 02
Dietitian intake and route assessment - Why
- Compare current oral or enteral intake with a patient-specific energy, protein, fluid and micronutrient prescription.
- Interpretation and limitations
- Meeting a recorded proportion of target demonstrates delivery; persistent shortfall triggers supplement, tube or parenteral-route review according to gut function.
- 03
Full blood count, ferritin and transferrin saturation - Why
- Identify anaemia, inflammation and iron deficiency that can impair recovery and exercise tolerance.
- Interpretation and limitations
- Interpret ferritin with CRP; iron deficiency may need intravenous replacement when surgery is near or oral absorption and tolerance are poor.
- 04
Urea, electrolytes, magnesium, phosphate, liver tests and glucose - Why
- Detect dehydration, losses, organ dysfunction and refeeding risk and provide a baseline for nutrition and steroid treatment.
- Interpretation and limitations
- Low phosphate, potassium or magnesium requires correction and slower monitored feeding when refeeding risk is present.
- 05
CRP, cultures and cross-sectional imaging when sepsis is possible - Why
- Separate inflammatory burden from uncontrolled abscess or perforation before elective anastomosis and immunosuppressive treatment.
- Interpretation and limitations
- An undrained collection is a source-control problem; a falling CRP after drainage supports but does not alone prove resolution.
- 06
Complete medication reconciliation - Why
- Record corticosteroid dose and duration, biologic or small-molecule name and last dose, anticoagulants, infection prophylaxis and interacting medicines.
- Interpretation and limitations
- The result should produce actual perioperative continue, convert, hold and restart instructions rather than a list copied into the notes.
- 07
Anaesthetic and functional assessment - Why
- Assess cardiopulmonary reserve, frailty, smoking, exercise capacity, adrenal risk and suitability for the proposed operation.
- Interpretation and limitations
- Poor reserve may change timing, level of postoperative care, prehabilitation and whether an anastomosis is appropriate.
04Applied reasoningWorked examples connecting principles to decisions.
01Worked case: nutrition and steroid optimisation before Crohn surgeryConvert measured deficits into a time-limited planA 34-year-old with an 8 cm fibrotic terminal-ileal Crohn stricture has three partial obstructions in two months. CT enterography shows no abscess or fistula. Weight has fallen from 69 kg to 63.5 kg in three months (8.0%), BMI is 19.1 kg/m², intake is about half usual, CRP 24 mg/L and haemoglobin 104 g/L. They have taken prednisolone 20 mg daily for six weeks and adalimumab; surgery is elective but should not drift indefinitely.+
- 1The colorectal surgeon, gastroenterologist and dietitian confirm a fixed short stricture without uncontrolled sepsis, quantify weight loss and intake, check iron indices, B12, folate, vitamin D, magnesium and phosphate, and document the exact steroid and adalimumab dates.
- 2The dietitian prescribes a low-residue oral diet plus liquid enteral supplements for ten days because the patient can pass stool and retain liquids. A patient-specific target is 1900 kcal and 85 g protein daily; intake charts show 82% of energy and 88% of protein target by day 4 without vomiting.
- 3Iron studies show ferritin 8 micrograms/L and transferrin saturation 9%, so the anaemia team gives ferric carboxymaltose 1000 mg IV over 15 minutes with product monitoring. The IBD team reduces prednisolone to 15 mg daily only after confirming stability. Medication history shows adalimumab 40 mg SC every two weeks, last given seven days ago; with no infection or abscess the MDT continues it preoperatively rather than imposing a washout. For this patient, recent nutritional depletion and continuing steroid exposure lead the MDT to choose a brief postoperative hold while assessing wound healing and infection risk against the risk of Crohn relapse; this is an individual elective-surgery decision, not a universal instruction to stop biologics for IBD surgery.
- 4At day 10 weight is 64.2 kg, phosphate and magnesium remain normal, haemoglobin is 111 g/L, CRP is 13 mg/L and the patient walks 400 m without stopping. Anaesthesia, stoma care and thromboprophylaxis plans are complete, and surgery proceeds rather than extending optimisation without a defined benefit.
- 5Because six weeks of prednisolone leaves glucocorticoid-induced adrenal insufficiency unexcluded and ileocaecal resection is major surgery, anaesthesia gives hydrocortisone 100 mg IV at induction then 200 mg over each 24 hours while nil by mouth. Once uncomplicated enteral recovery is established, give double the pre-surgical prednisolone dose—30 mg daily—for 48 hours, then return to 15 mg and resume the IBD taper. Following the individual MDT plan, the adalimumab dose due during early postoperative recovery is withheld and treatment is restarted on postoperative day 14 only after the wound is healed, sutures are out and there is no drainage, erythema, swelling, organ-space infection or other active infection. Pathology confirms a fibrotic stricture; oral intake meets target by day 4 and day-30 review verifies no leak or abscess and records the actual biologic restart.
02Ulcerative colitis on anti-TNF before elective surgeryAvoid an automatic biologic washoutA 42-year-old with dysplasia in ulcerative pancolitis is clinically stable on infliximab, takes no corticosteroid and has no fever, collection or other active infection. Elective proctocolectomy is planned two weeks after the next scheduled infusion.+
- 1Confirm the indication for surgery, nutrition, full blood count, renal and liver tests, CRP, infection history and the exact infliximab schedule. Screen for a current infection rather than using the biologic name as a surrogate.
- 2Discuss at IBD and surgical MDT. Apply the BSG recommendation that anti-TNF therapy can continue in the preoperative period for ulcerative colitis, and do not cancel an otherwise ready operation to impose an arbitrary washout.
- 3Document perioperative infection surveillance, antimicrobial prophylaxis according to the operation, mechanical and pharmacological VTE prevention and the intended postoperative level of care.
- 4The patient receives the scheduled infusion and undergoes the planned operation. At day 7 there is no fever, wound infection or organ-space collection; histology confirms high-grade dysplasia without invasive cancer.
- 5The IBD and surgical teams document whether any continuing anti-TNF indication remains after colectomy. Medication reconciliation at discharge prevents an infusion being given or omitted accidentally.
03Complete obstruction with nutritional depletionResuscitate and control the obstruction while beginning supportA 57-year-old with Crohn disease, 14% six-month weight loss and current prednisolone 30 mg develops faeculent vomiting, absolute constipation, pulse 122/min, BP 94/58 mmHg and lactate 3.4 mmol/L. CT shows a closed-loop small-bowel obstruction with reduced mural enhancement.+
- 1Start ABCDE resuscitation, keep nil by mouth, establish intravenous access, correct fluid and electrolyte losses, decompress the stomach, measure urine output and call colorectal surgery and anaesthesia immediately.
- 2Treat possible ischaemia and sepsis under the local emergency antimicrobial and operative protocol. Nutrition screening and steroid history occur in parallel and must not delay surgery for a threatened bowel.
- 3Give hydrocortisone 100 mg IV at induction, then 200 mg over each 24 hours during major emergency surgery and while nil by mouth, because six weeks of prednisolone 30 mg makes HPA suppression likely and cannot be assessed before source control. This stress-cover regimen supersedes simple 1:4 maintenance substitution during the infusion; do not abruptly stop corticosteroid exposure.
- 4At laparotomy, 35 cm of non-viable ileum trapped by an inflammatory band is resected and a stoma is formed because shock, high-dose steroid exposure and depletion make an anastomosis unsafe.
- 5After source control, the nutrition team advances enteral intake as gut function returns and monitors phosphate, magnesium, potassium and glucose. Lactate is 1.4 mmol/L at 12 hours, creatinine returns to baseline by day 3, and the MDT sets a later reconstruction and disease-control plan.
05Relevant medicines and safetySpecific regimens and precautions where medicines are relevant.
Perioperative hydrocortisone: maintenance conversion and major-surgery cover
For maintenance arithmetic, prednisolone 5 mg equals hydrocortisone 20 mg; therefore prednisolone 20 mg/day equals hydrocortisone 80 mg/day. This is not the whole major-surgery plan. In an adult taking prednisolone at least 5 mg/day for at least 4 weeks with unexcluded HPA suppression, corrected Woodcock Table 2 uses hydrocortisone 100 mg IV at induction followed immediately by 200 mg/24 hours by continuous IV infusion while nil by mouth, then double the pre-surgical enteral glucocorticoid dose for 48 hours if recovery is uncomplicated.Document dose, duration, recent courses, operation magnitude and oral absorption with anaesthetic/endocrine input. The 200 mg/24-hour stress infusion covers the nil-by-mouth period; do not add a separate calculated maintenance infusion unless the specialist plan explicitly requires it. Monitor infection, glucose, blood pressure, sodium, potassium, mental state and wound healing, and taper from the defined transition rather than stopping abruptly.
Ferric carboxymaltose for the worked iron-deficiency case
For the 63.5 kg adult with haemoglobin 10.4 g/dL in the worked case, the Ferinject simplified table gives a total need of 1000 mg. Give 1000 mg iron (20 mL) as one IV infusion over at least 15 minutes, diluted only in no more than 250 mL compatible 0.9% sodium chloride and maintaining at least 2 mg iron/mL; the dose is below 20 mg/kg and the 1000 mg weekly maximum.Confirm iron deficiency and exclude hypersensitivity to parenteral iron. Administer where anaphylaxis can be treated, observe for at least 30 minutes, avoid extravasation and monitor phosphate when repeated high doses or risk factors make hypophosphataemia likely. A routine preoperative full blood count can assess readiness, but formal haemoglobin reassessment of iron repletion should be at least 4 weeks after the final Ferinject dose.
06Checking understandingVerify the reasoning, revisit uncertainties and apply feedback.
- Reweigh at defined intervals and record actual intake against prescribed energy and protein targets; “dietitian involved” is not evidence that support was delivered.
- During nutrition escalation, monitor fluid balance, glucose, potassium, magnesium and phosphate according to refeeding risk and replace deficits promptly.
- Track haemoglobin and the treated deficiency, CRP and source-control imaging where relevant, while recognising that biomarker improvement does not replace examination.
- Record the daily corticosteroid dose, intravenous-to-oral conversion, glucose and infection status, and a named taper owner after discharge.
- For each biologic or small molecule, document last dose, perioperative decision, reason, infection criteria for restart and actual restart date.
- Audit postoperative wound or organ-space infection, anastomotic leak, ileus, VTE, high-output stoma, renal injury, length of stay and 30-day readmission against the preoperative risk plan.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Albumin is not a nutrition score
Inflammation, capillary leak and protein loss lower albumin, so it must be interpreted with intake, weight change, muscle state and CRP.
Optimisation needs a deadline
A measured ten-day gain can be valuable; repeated delay without targets may allow obstruction, sepsis or disease progression.
The functioning gut sets the route
Oral or enteral feeding is preferred when safe, while obstruction, intolerance or intestinal failure may require another route.
Equivalence is not stress cover
A 1:4 prednisolone-to-hydrocortisone conversion prevents under-replacement while nil by mouth. Major surgery in someone with unexcluded glucocorticoid-induced adrenal insufficiency additionally needs the risk-based anaesthetic cover and transition specified by the corrected perioperative guideline.
Biologic decisions require a restart plan
A documented hold without criteria for resumption can become prolonged undertreatment after recovery.
Steroid burden is modifiable risk
Reducing exposure before elective surgery can improve risk, but an abrupt taper that triggers active disease defeats the purpose.
08Common pitfallsFrequent interpretation and management errors.
- 01
Using albumin alone to diagnose malnutrition confuses inflammatory severity with nutrient intake and misses sarcopenia at a normal BMI.
- 02
Prescribing “nutritional supplements” without an energy and protein target, intake record or tolerance check cannot show whether the intervention worked.
- 03
Insisting on routine exclusive enteral nutrition for every Crohn operation overstates current evidence and may be unsafe in high-grade obstruction.
- 04
Stopping sustained prednisolone abruptly before surgery risks adrenal insufficiency and inflammatory deterioration.
- 05
Using the maintenance-equivalence calculation as the entire major-surgery prescription can under-treat adrenal stress after sustained prednisolone; conversely, stress cover should follow exposure and operative risk rather than an undifferentiated dose for every patient.
- 06
Automatically withholding all biologics for a fixed interval ignores disease-specific evidence, including BSG support for anti-TNF continuation before ulcerative-colitis surgery.
- 07
Delaying surgery for nutrition or a drug washout in peritonitis, ischaemia or complete obstruction sacrifices source control to an elective optimisation rule.